Friday, July 16, 2010

The tough life of a sprinter

I wrote a while back (in 2008) about how we all have different body types, and how our body type predisposes us to do well in some cycling events but not others. So many of us keep banging away at things we aren't suited for, because we don't know ourselves well.

I know I did; trying to race my bike against real climbers in big, hilly road races and getting dropped almost every time. It took me many years to learn that I am, in fact, a sprinter. All that time I thought I was merely a slow, or undertrained at best, climber. It was a relief to finally understand what type of rider I actually was; one not meant to do well on big climbs! And it's taken me several more years to learn that I am not just a sprinter, but probably very close to a 100% pure sprinter. Well, 80% to be specific.
According to the experts extreme sprinter body-types have as much as 80% of their muscle fibers in the form of fast-twitch muscle fibers (usually called "type 2") and the other 20% in slow-twitch muscle fibers ("type 1"). Those extra fast-twitch fibers contract much more strongly than slow-twitch fibers, which makes sprinters so fast, but they also tire much, much faster. Don't I know that!
In the past my best guess, based on my feelings of how I compared with other cyclists, was that I was "about 60% fast-twitch, 40% slow-twitch." Why? Because I could climb fairly well, but sprint better. But I no longer feel that guess was right: I now think I am not only an extreme sprinter body-type, with close to 80% fast-twitch muscle fibers, but even more sprinter-skewed with a large portion of that 80% in the form of "type 2b" muscle fibers. Yikes!
Wait, I didn't explain what "type 2b" means. OK, the fast-twitch muscle fibers are further defined by "type 2a" and "type 2b" designations (and even "type 2x" which is sort of in between 2a and 2b). Both are fast-twitch but they have some differences too:
Type 2a muscle fibers
These are fast-twitch fibers ("middle distance"), but due to their construction they are also very trainable. In fact, they are so trainable they can literally morph from fast-twitch characteristics to become slow-twitch over time, with the right training. Type 2a fibers are red in color (as are type 1) because they have high levels of myoglobin and are thus more aerobic (oxygen burning). Dark meat!
Type 2b muscle fibers
These also fast-twitch fibers (short distance), but rather set in their ways. They can only be trained to be stronger but never abandon their sprinter characteristics. I train these with "L7" jumps; short sprints at my absolute maximum possible power for about 6 to 10 seconds. Some people use weight training, but not I. Type 2b fibers are white in color and are anaerobic (no oxygen). White meat!
OK, back to me. How could I even begin to guess at my muscle-fiber composition without a muscle biopsy? Sure, cycling gives us chances to compare ourselves against other cyclists, but how reliable is that? Well, since I started training with a bike-mounted power meter I have had a whole new way of measuring and testing my performance versus others' performance: "Power profiling." I have been testing and logging my power from hundreds of intervals over almost two years now, and here's how my power profile compares against a huge number of other cyclists tested and entered into a big database:
This simplified graph shows how my best tested power ranks against the power of other cyclists. The higher my power profile bars rise in this graph the better I compare against those other cyclists in that length of interval in the four interval lengths at the bottom of it: 5 second, 1 minute, 5 minutes and 60 minutes). So, per the graph, my 5-second interval power is by far my best, relative to other cyclists. I'm not bad in the other intervals, but I won't win any races in them either.
In short, I'm a Ferrari. OK, maybe just a Honda S2000 (I am a small sprinter after all!). I have relatively lots of power at the "top end," but not much at the longer intervals. That's why my power profile slopes downward to the right; a strong endurance athlete with lots of type 1 muscle fibers would have a profile sloping upward to the right; they can't sprint to save their lives, but they can ride hard all day long. A generalist would have a fairly flat profile, perhaps with a bit of a drop at either end, reflecting their adaptability to varying conditions.

Unfortunately being a pure sprinter in cycling is a major drawback in most bike races. The best "sprinters" actually have a flatter ("general" or "all-around") power profile... though with a nice kick up on the left of that graph. They are fast enough in longer races that they can draft behind the type 1 endurance guys without getting dropped, then sprint around them for the win. I can sprint faster than those guys (in theory, all else being equal), but I usually get dropped long before the finish line so that doesn't help me much! In fact I've written about how my sprint power in an actual race is much lower than during my sprint training, even when I win, because the sprint always comes after a long desperate struggle for position at the front of the pack.
Now we all know that training is supposed to make us stronger, and it does. It also has this amazing capacity for changing our very physiology. I decided a few years ago to shift my physiology through training to make myself a different type of cyclist; a cyclist with better endurance, albeit at the expense of some of my sprint power. That can be done by training the type 2a fibers to act more like type 1 fibers. The type 2a fibers can literally be "recruited" to become more red... meaning they become more aerobic in function. Weird!
The training I've been prioritizing the last three years consists of lots of long "L4" (level 4) intervals. These L4s are simply intervals ridden at or near our aerobic threshhold for about 15 to 60 minutes. Painful but productive. I do about seven or eight 20-minute L4 intervals every week, year round. And it has worked as the graph below shows.

The blue line shows my power as it was last year. The red line shows my power as it is this year. The biggest shift has been in my sprint power, which is sadly lower. But there's a tiny improvement in my 20-minute power (enlarge the image to see it!). You might think that very tiny improvement is not worth the big drop in sprint power, but it is important to consider this: My tiny 20-minute power gain is multiplied over a full hour of riding (I ride my L4s at my 1-hour power), while the sprint power is just subtracted from a few seconds. My total potential power is now significantly higher than before.
All that hard training has changed my body type, and better equipped me to handle the aerobic demands of cycling. I am still not, and never will be, en endurance athlete... I'm still a sprinter who can get dropped, but it's less likely and I'll be fresher for the final sprint if I'm still there at the finish.

Wednesday, July 7, 2010

Power training: Current vs. average power display

Many of my teammates and I mount power meters on our bikes that display our pedaling power during the "intervals" we do during training rides. This is much more useful than using our heart-rate to try to pace ourselves. There are lots of subtle details, though, that affect how we ride during power-based intervals, like what data to display on the meter's LCD.

So, if we're riding, say, a 20-minute interval, we press the "interval mode" start button and then constantly adjust our pedaling effort so that the interval's resulting average power reading (in Watts) is within our 20-minute training power zone. If the reading is too low we pedal harder; if too high we back off a bit. We then dutifully record this reading in our training logs for future reference. Just for an example, here are my training zones (we rarely train below Level 4 unless we're too dog-tired to do any better):
  • Level 4: 246-285W
  • Level 5: 286-332W
  • Level 6: 333-600W
  • Level 7: as high as possible!
It's very hard to pedal 100% smoothly. So most of my teammates who train with power meters set them to display the average power of the interval they're riding. That smoothes out the natural peaks and valleys in the power we produce so the value displayed doesn't swing up and down as wildly. And since we can only record the average power in our logs (not current, of course), displaying the average power seems to make sense. The down-side is that in long intervals the inevitable power variances, below and above our training zones, don't really show on the average display. I've noticed most guys who use average display tend to have huge power spikes on short hills, and very low power on descents. Not a problem on a steady climb (like, say, Bonny Doon Road) but definitely less ideal on a route with rolling hills (like Swanton Road or Highway 1).

Others of us use the current ("instantaneous") power display. It shows the power we're producing at any given moment. I do this to learn how to pace myself as smoothly as possible. The experts agree, as do my legs, that smooth and steady is more efficient. And more efficient is faster and more sustainable over time. Per Matt Russ: "A variable effort is more fatiguing to the body when compared to an even, steady effort." I am pretty much always able to hit my power training zones on every interval, day after day, week after week. I suspect my even pacing gets some credit for that.

So, which is best? Neither; both can work just as well. Try both and see how they work for you...

OK, I admit I prefer current power since our intervals are designed for a specific power level, not the average of wildly fluctuating power. And constant power spikes tire us out; that can jeopardize our power during a tough workout. Check out the following graphs, which charted my power during two similar intervals (the yellow line is power in Watts):

Which one do you think yielded the best average power? The left one did, which may not be surprising if you look at how smooth the yellow power line is on it, compared with the jumpy yellow power line on the right graph. I hope those graphs make my point for me: Use the current power display and try to keep the power exactly where you want the average to be when you're done with the interval.

But it brings up another topic: pacing strategies for time-trials (solo races against the clock). The steady pace that is best for intervals isn't always best for TTs (or other races). But even then I'm convinced current power display is better because it allows us to nail our power level exactly to suit the TT course. But... that is a big topic worthy of a separate blog post. In the meantime, here are some links to pacing articles:
Happy pacing!

Thursday, July 1, 2010

No future in mountain-biking for me?

When I sold my trusty '98 Stumpjumper, in December 2008, I thought I'd soon be upgrading to some fancy new mountain-bike, with the latest and greatest technology. Well, that hasn't happened, and it may never, because of a number of factors that all played a role in making me question whether I even have a future in mountain-biking.

OK, first there's the whole issue of buying another expensive bike... one I'd use just rarely. But I do know what I'd get, roughly: A 29-inch-wheeler with full suspension (I've decided no more hard-tails), SRAM 20-speed drivetrain, and just an aluminum frame (no need for carbon-fiber). Tubeless tires would be nice too. What, maybe $3,000 to $4,000 total? Uh, maybe even more?

Lots of money for a bike I'd use... how often? All my training is on the road with my team-mates or while riding to work. Not on dirt where it's harder to pace yourself due to rough trails, or find enough long, smooth climbs. So, mostly just for racing then.

When we do well enough in mountain-bike races we eventually get our racing category upgraded. And in every mountain-bike race I know of the higher-category racers have to race longer. For me, as a sprinter, that is the kiss of death for my chances in races. When I was in "Sport" (now called Category 2), I usually did races that were about 1.5 to 2.5 hours long. But now as a "Cat 1" I not only have to race against faster guys, but race longer... a double-whammy! I am a sprinter, not a marathoner!

Unless I race short-track: Short, intense races rather like a dirt criterium. Now we're talking! But the only race in Nor Cal that I know of with a short-track event is Sea Otter Classic, and not every year either.

So... an expensive bike I'd use once a year or so.

Like I say, no future in mountain-biking for me.